Thermostatic unit



Feb. 17, 1942.

J. E. WOODS THERMOSTATIC UNIT Filed Feb. 10,

j'z'ven/ior MM 2 L 5 a w 3% 6 M N L w 3w 3 a m w x\ m f. M 4/ 7 g V 5 6 v v t: x Z 2 w R m awxx Q r 6 Zmm Mines;

Patented Feb. 17, 1942 OFFICE 'rnEnMosTA'Trc'umT John E. W Brookline; Mass assignor to coda, Cliiford Manufacturing 00., Boston, Mass a corporation of Delaware Application February 10, 1940, Serial No. 318,268

- 2 Claims. (01. goo-14o) The present invention relates to a thermostatic unit particularly designed for insertion in an open cooking vessel where it is desired to maintain water or the like under atmospheric; pressure at the boiling point. or in close relation thereto. Such a unit, by cutting down on .the input of heat when the boiling point is reached, will main-'- tain temperature for cooking without an excess of heat which merely serves to boil the water away at a faster rate without accomplishing any useful cooking function.

I have found in connection with such a unit that in order to automatically compensate for changes in the boiling point caused by diflerences in atmospheric pressure which may be created by changes in the barometer or by changes in the altitude, it is necessary to provide a type of control which shall automatically fluctuate as the atmospheric pressure changes, and thus maintain the boiling point automatically at whatever (temperature may be required at any given atmospheric pressure.

With this in view, I have designed a simple, compact, unitary structure which may be immersed directly inthe cooking water without injury either to the unit or to the food in process of cooking, and which when properly connected with a source of heat such as an electric coil, will control the coil through an appropriate relay and switching mechanism.

The drawing illustrates ment of the invention in elevation of the unit.

Referring particularly to the drawing, the unit as a whole is housed in a cylindrical casing ll threaded at opposite ends at l2 and It. On the inner end of the casing as threaded at I2 is attached a sleeve IS, on which is mounted a generally radial flange l8 carrying a cap which forms the outer wall of a thermostatic chamber,

the movable wall of which is constituted by a diaphragm 22 sealed to the through a solder bond 24.

the preferredembodi- The central portion a complementary contact 38 is pivoted" at 4|! .the boiling water rat the most economical be connected through contact is provided with 18 and ill from which ment of the diaphragm. The inner wall of the casing about the contacts and electrical connections may be lined with a fibre tube 46, and each a terminal connection extend .leads 52 and 54 through a head 56 threaded upon the opposite end of the tube. From this point the leads may appropriate terminals with a relay and switch for controlling the heat input.

It will be noted that the parts may be readily retained in assembled relationship by providing 2 a spring 60 received within the casing and interposed between the block 30 which has a shoulder 62 held against a complementary shoulder within the casing, and a seat 64 connected to the sleeve l6 by a soldered joint 66. When the sleeve is threaded upon the end of the casing the spring forces the block into flrm contact with the shoulder and maintains it in this relationship.

I propose to flll the thermostatic chamber in the head in such a'fashion that it normally operates on the vacuum side, employing the natural curvature of the diaphragm to open the contacts. With this construction, so long as the vacuum exists within the chamber, the contacts will remain closed, but upon elevation of temperature or failure of the diaphragm which'causes the form of a sectional interior of the cap '45 of the diaphragm carries a threaded member 26 mospheric pressure.

the vacuum to fail, the contacts automatically open.

I accomplish this result by subjecting the chamber through the opening 10 to a vacuum, and thereafter inserting therein an appropriate amount of liquid having a somewhat-higher boiling point than water in order that the vapor pressure of the contained liquid shall overcome the vacuum and permit the diaphragm to open the circuit at the boiling point of water atwhatever atmospheric pressure may exist, since the outer surface of the diaphragm 22 is exposed to at- This can be accomplished by employing xylene or toluene or mixtures of the two. In adjusting the unit for proper temperature conditions, the lower end of the unit and engaged by the free end of the stem 28- to be actuated by movement of the stem under the containing the thermostatic chamber may be immersed in boiling water, and the sleeve I6 is then adjusted on the threaded connection until the contacts are caused to break at the desired temperature at which the the headand sleeve may be soldered as indicated at I2 to retain the adjustment.

unit operates. Thereafter,

What is claimed is:

1. An immersion unit for controlling heat input, which comprises a generally tubular casing. a support of insulating material fixedly mounted within the casing and having a circuit contact mounted thereon, a pivoted'armmounted adjacent thereto and carrying a complementary con tact. a head connected to the casing and having a thermostatic chamber therein, a diaphragm constituting the movable wall or the chamber, an operating rod connected with the movable wall and contacting the pivoted arm, thermostatic fluid within the chamber vaporizable at the temperature range, a spring interposed between the insulating material and the head, and means ior adjusting the head longitudinally of the casing to predetermine the temperature of operation.

2. An immersion unit for controlling heat input, which comprises a thermostatic chamber having an outer wall and a movable diaphragm forming the inner wall, a tubular mounting connected with the outer wall and constructed to apply atmospheric pressure to the diaphragm when the thermostatic chamber is immersed, a medium within the chamber vaporizable at the operating range to operate the diaphragm at approximately the boiling point of water at any atmospheric pressure, circuit contacts enclosed within the tubular mounting, and connections between the diaphragm and the circuit contacts ior opening the contacts upon expansive movement or the diaphragm.

JOHN E. WOODS. 

